#include <iostream>
#include <string>
#include <algorithm>

using namespace std;

int main()
{
    int n;
    string s1, s2;
    string s;

    cin >> n;
    cin >> s1 >> s2;

    int prev1 = -1, prev2 = -1, ret = 0x3f3f3f3f;
    for (int i = 0; i < n; i++)
    {
        cin >> s;
        if (s == s1) // 去前面找最近的 s2
        {
            if (prev2 != -1)
            {
                ret = min(ret, i - prev2);
            }
            prev1 = i;
        }
        else if (s == s2) // 去前面找 s1
        {
            if (prev1 != -1)
            {
                ret = min(ret, i - prev1);
            }
            prev2 = i;
        }
    }

    if (ret == 0x3f3f3f3f) cout << -1 << endl;
    else cout << ret << endl;

    return 0;
}